The present invention relates generally to railroad vehicles and particularly to steering railroad trucks or radial bogies having unitized brakes.
Generally, unitized brakes have very limited brake shoe stroke due to the nature of their design. The limited brake shoe stroke available from unitized brakes makes it more difficult to apply unitized brakes on radial bogies than on non-radial bogies, since greater brake shoe stroke or a special mechanism is required to compensate the variation of the clearance between the brake shoe and wheel due to the wheelset steering. Due to the steering function of radial bogies, a bogie frame-mounted unitized brake generally need about 20 mm of extra shoe clearance, a difficult requirement to meet with existing prior art bogie designs. The present inventors have recognized a need for improvements in radial bogie design.
The present invention meets the above-mentioned need by providing a railroad truck or bogie with two or more powered or unpowered wheelsets and unitized brakes mounted on steering beams for leading and trailing wheelsets. The steering beam-mounted unitized brake of the present invention is guided with the wheel. The present invention further includes for each brake a hanger bracket that is attached on the bogie""s side frame to carry the vertical shoe reaction force.
Although the present invention is not limited to specific advantages or functionality, it is noted that since the steering beam-mounted unitized brake will be guided with the wheel, extra shoe clearance is not required. Additionally, for each brake, since the hanger bracket carries the vertical shoe reaction force to the bogie frame, the steering beam is not loaded in torsion, thereby reducing total steering beam loading and wear.
In one embodiment, provided is a radial bogie for rail vehicles comprising a frame having longitudinally extending side frames laterally spaced by transoms, the side frames defining a longitudinal axis and having leading and trailing ends. Included are leading and trailing wheelsets with axles supported on the frame, and first and second steering beams for pivotally guiding the wheelsets. The first steering beam is pivotably mounted on the frame behind the leading wheelset away from the leading end of the frame, and the second steering beam is pivotably mounted on the frame behind the trailing wheelset toward the trailing end of the frame. Traction links are connected between the wheelsets and the steering beams, and an inter-axle linkage is connected between the steering beams. Unitized brakes are mounted on the first and second steering beams.
In another embodiment, provided is a radial bogie for rail vehicles comprising a frame having longitudinally extending side frames laterally spaced by transoms, the side frames having side posts and defining a longitudinal axis. Included are two end wheelsets with axles supported on the frame, the two end wheelsets being pivotably mounted on the frame, and a center wheelset with an axle supported on the frame between the two end wheelsets. The center wheelset is substantially unpivotably connected to the side posts by traction links and is movable laterally to the longitudinal axis. Included also are steering beams for pivotally guiding the end wheelsets, each one of the steering beams is pivotably mounted on the frame behind a respective one of the end wheelsets, additional traction links connected between the end wheelsets and the steering beams, and an inter-axle linkage connected between the steering beams. A first set of unitized brakes is mounted to the steering beams.
In still another embodiment, provided is a radial bogie for rail vehicles comprising a frame having side posts, a leading end, and defining a longitudinal axis, and including first, second and third wheelsets having axles being elastically supported on the frame, and a pair of steering beams, one each located behind the first and third wheelsets away from the leading end of the frame and mounting a first set of unitized brakes. The radial bogie includes a second set of unitized brakes for braking the second wheelset. Traction links couple the first and third wheelsets to the steering beams and the second wheelset to the frame. Included also is an inter-axle link coupling rotary motions about vertical axes of the steering beams to provide opposite transverse movement of the first and third wheelsets upon traversing curves, wherein each of the first set of unitized brakes includes an active lever and a brake shoe pivotably connected to a hanger, the active lever being connected to the brake shoe, and the hanger being pivotably connected to the frame, and wherein each of the second set of unitized brakes includes an active lever and a brake shoe pivotably connected to a hanger, the active lever being connected to the brake shoe, and the hanger being pivotably connected to a respective one of the side posts.
In still yet another embodiment, provided is a railroad locomotive of the type comprising a carbody supported by at least one self-steering radial bogie having a frame having longitudinally extending side frames laterally spaced by transoms, the side frames defining a longitudinal axis and having leading and trailing ends. Included are leading and trailing driven wheelsets with axles supported on the frame, and first and second steering beams for pivotally guiding the wheelsets. The first steering beam is pivotably mounted on the frame behind the leading wheelset away from the leading end of the frame, and the second steering beam is pivotably mounted on the frame behind the trailing wheelset toward the trailing end of the frame. Traction links are connected between the wheelsets and the steering beams, and an inter-axle linkage is connected between the steering beams. Unitized brakes are mounted on the steering beams.
In still another embodiment, provided is running gear for rail vehicles comprising at least one bogie having a frame having longitudinally extending side frames laterally spaced by transoms, the side frames defining a longitudinal axis and having leading and trailing ends. Leading and trailing wheelsets with axles are supported on the frame. Included are first and second steering beams for pivotally guiding the wheelsets. The first steering beam is pivotably mounted on the frame behind the leading wheelset away from the leading end of the frame, and the second steering beam is pivotably mounted on the frame behind the trailing wheelset toward the trailing end of the frame. Traction links are connected between the wheelsets and the steering beams, and an inter-axle linkage is connected between the steering beams. Unitized brakes are mounted on the steering beams.
These and other features and advantages of the invention will be more fully understood from the following description of a preferred embodiment of the invention taken together with the accompanying drawings. It is noted that the scope of the claims is defined by the recitations therein and not by the specific discussion of features and advantages set forth in the present description.